Lesson 3: Accessory Structures of the Skin Flashcards
Glands that secrete oils (sebum) that lubricate and protect the skin and hair, located in dermis, not found in hairless skin, some open into hair follicles, but some open directly onto the skin (lips, glans penis, labia minora, tarsal glands of the eye lids)
Sebaceous glands
Glands that secrete salt and water as sweat
Sweat glands
What are the two different types of sweat glands?
Merocrine (Eccrine) and Apocrine
These sweat glands are found all over the skin, high concentrations found in palms and soles, open directly onto the surface of the skin as a sweat pore, activated in response to hyperthermia or emotional stress
Merocrine (Eccrine) sweat gland
Large sweat glands that develop during puberty and located mainly in armpits and genital areas, the duct opens into a hair follicle, DO NOT contribute to thermoregulation but can be activated due to emotional stress
Apocrine sweat gland
Modified apocrine glands, located deep in the auditory canal of the external ear, can be combine with sebaceous gland or open independently and directly into the external auditory canal
Ceruminous glands
Earwax, formed by the combined secretions of the ceruminous and sebaceous glands
Cerumen
What is hair?
An accessory structure in the integumentary system, grows from the depths of the dermis but has its origins in the epidermis, consists of dead, keratinized epithelial cells connected by extracellular proteins
What are the functions of hair?
Protects from UV damage, advertises sexual maturity, retains heat, and sensory role
What is the anatomy of the hair?
Shaft, root, and the bulb
What are the layers of the shaft?
The medulla (inner most layer), cortex (layers of elongated cells, forms significant part of the hair structure), and cuticle (the outer most layer of the hair strand) - extend to the root and bulb
Region of hair extending beyond the epidermis
Shaft
What are the three important structures found only in the bulb of the hair?
Papilla (inner layer that contains blood vessels and connective tissue), matrix (cells that surround the papilla of the hair, divide to give rise to new cells within hair), and melanocytes (contain melanin)
What does the hair follicle contain?
The root and bulb
What is the hair follicle composed of?
Epithelial root sheath and a dermal root sheath
What happens to the hair in response to the cold?
Tiny muscles called arrector pili are innervated and contract all at once, causing the hair to “stand up straight”
A clear plate of dead keratinized epidermal cells
Nail
Translucent, visible portion of the fingernail that lies dorsally at the distal end of the digit, overlying the nail bed
Nail plate
What are the three parts of the nail plate?
Root (proximal end of the nail, lies beneath the skin and extends several mm into the finger
Body (main portion of the nail that overlies the nail bed)
Free edge (distal overhang of the nail plate over the pulp of the digit)
A specialized form of epithelium beneath the nail plate. Adds material (in form of keratin) just below the nail, making it thicker and stronger
Nail bed
White, half-moon-shaped area at the proximal end of the nail.
Lunula
Below the nail plate, layer of keratinocytes that surround the nail root. Major part of active nail growth
Nail matrix
Below the nail plate, underneath the free edge of the nail, thickened area of skin made from the stratum corneum. Secures the nail to the fingertip
Nail hyponychium
Type of receptor? Responds to touch, found in dermis of hairless skin, in abundance in hands, feet, lips, and external genitalia, egg-shaped and encapsulated
Tactile corpsucles (Meissner’s corpuscle)
Type of receptor? Responds to pressure, located throughout body in the dermis, subcutaneous layer, and deeper regions, oval and encapsulated
Pacinian corpuscle (lamellated corpuscles)
Type of receptor? Responds to touch (slowly adapting), located in fingertips, hands, lips, and external genitals, flat saucer-shape and free nerve
Merkel disc
Type of receptor? Responds to extreme temp; physical, mechanical, or chemical irritation, located in epidermis (skin) and mucous membranes, bare nerve endings
Nociceptor
Type of receptor? Responds to stretching, located in dermis in hands and soles of feet, elongated and encapsulated
Ruffini
Type of receptor? Responds to the movement of hair, wrapped around a hair follicle, hairy skin, free nerve ending
Root hair plexus
